Multiple twisters that twist a yarn several times while a single spindle shaft is driven and rotated once are conventionally known and are configured in such a way that one driving belt is wound across a large number of spindle shafts arranged in a line to drive the spindle shafts concurrently.
In such concurrent-drive type multiple twisters driven by the belt, since the driving belt is driven in the state that the driving belt pressure-contacts the spindle shafts and imparts a radial force to the bearing portions of the spindle shafts, a high level of noise may occur or a significant amount of power may be lost because the one drive belt is used to drive a large number of spindle shafts.
Thus, in order to reduce noise and power losses, an individual-spindle-drive type multiple twister has been proposed in which a motor is provided for each twisting unit to directly drive the spindle shaft.
In one of the configurations using the motor to directly drive the spindle shaft in the above manner, the motor is configured by, for example, mounting a rotor onto the spindle shaft and disposing a stator opposite to the rotor, and the rotor is composed of a permanent magnet.
In recent years, to increase twisting efficiency and thereby improve productivity, and so on, the magnetic force of the permanent magnet constituting the rotor has been increased to enhance the drive power of the motor and thus the high rotational speed of the spindle shaft is obtained.
The motor that directly drives the spindle shafts can be configured by, for example, securing a permanent magnet, acting as a rotor, to the spindle shaft, securing a core coil, having an iron core and acting as a stator, to the inner circumferential surface of a housing covering the outer circumferential surface of the spindle shaft, and configuring the rotor and the stator mutually opposite to each other, and then, the motor is assembled by inserting the spindle shaft with the rotor fixed thereto into the housing with the stator fixed thereto, so that the spindle shaft is rotatably supported by a bearing after the motor is assembled.
In the motor configured in this manner, if the magnetic force of the permanent magnet constituting the rotor is increased, an attractive force generated between the rotor and the iron core of the coil constituting the stator increases, and thus, when the spindle shaft is inserted into the housing, if the rotor approaches such as the iron core of the stator before the spindle shaft is supported by the bearing, the rotor and the stator attract each other strongly and may stick to each other or hinder the spindle shaft from being inserted into the bearing appropriately, thereby preventing the motor from being assembled easily.
In addition, to increase twisting efficiency and thereby improve productivity and so on, the magnetic force of the permanent magnet constituting the rotor is increased to enhance the drive power of the motor and thus the motor notes at the high rotation speed, however, to allow the motor to provide sufficient drive power, it is important even during high rotation speed to prevent the motor from becoming hot and prevent magnetic interference between the housing of the motor and the internal magnet. In addition, in case the motor does become hot, it is important to cool it efficiently.
Furthermore, when using the motor to drive the spindle shaft stably at high rotation speed, it is important to minimize the deflection of the spindle shaft by supporting the spindle shaft firmly or reducing the interval between the motor and a rotating disc that rotates integrally with the spindle shaft.
In addition, in the configuration using the motor to directly drive the spindle shaft, the spindle shaft is rotatably supported via a bearing on a supporting base fixed to a frame, and if, for maintenance and so on, a lubricating oil is supplied to the bearing that supports the spindle shaft, this operation is performed after allowing the spindle shaft to protrude upward from the supporting base. If the apparatus is configured in such a way that the lubricating oil is supplied to the bearing after allowing the spindle shaft of a twisting unit to protrude upward from the supporting base, as described above, the lubricating oil supply operation is cumbersome and a larger space is required in the vertical direction, resulting in the need to increase the size of the individual-spindle-drive type multiple twister.
Thus, a lubricating oil supply passage may be formed in a supporting portion for supporting the spindle shaft so that the lubricating oil can be externally supplied while the spindle shaft is being supported by the bearing. However, in the configuration using the motor to directly drive the spindle shaft, the spindle shaft is supported both above and under the motor,and thus, if the lubricating oil supply passage is formed above the bearing, the required space from the motor to the rotating discover the motor must be increased, and this increases the height of the twisting unit, thereby reducing the rotational stability when the spindle shaft is rotated at high rotation speed.
It is thus a first object of the present invention to provide an individual-spindle-drive type multiple twister that enables a motor that directly drives a spindle shaft to be easily assembled despite the attractive force between a rotor and a stator and that enables increase of the driving power of the motor by increasing the magnetic force of the permanent magnet constituting the rotor, thereby improving twisting efficiency and, accordingly, productivity.
In addition, it is a second object of the present invention to provide an individual-spindle-drive type multiple twister wherein a motor with a permanent magnet constituting a rotor and having a high magnetic force can provide sufficient driving force, and wherein the spindle shaft can rotate stably at high rotation speed.
Furthermore, it is a third object of the present invention to provide an individual-spindle-drive type multiple twister that restrains the height of the twisting unit to enable the spindle shaft to rotate stably at the high rotation speed, and that enables a lubricating oil to be supplied reliably and simply to a bearing.